1. Field of the Invention
The present invention relates to an interlayer insulation film used for multilayer interconnect of a semiconductor integrated circuit and a method of manufacturing the same. More particularly, the present invention relates to a polishing stopper film used for Cu multilayer interconnects and a method of manufacturing the same.
2. Description of the Related Art
Aiming at faster semiconductor integrated circuits with more sophisticated features, miniaturization of the integrated circuits has been advanced. In the past, Al had been used as a material for multilayer interconnects of semiconductor integrated circuits. As wiring has become microscopic and long-distance, however, disconnection troubles which are caused by electromigration arising from increased current density, and signal delays which are caused by electrical resistivity of Al and a dielectric constant of an insulation film, have become issues.
It is Cu that has been brought to attention as a next-generation material for multilayer interconnects. Cu is tolerant to disconnection troubles and its electrical resistivity is smaller than Al. In 1997, a technology called Dual-Damascene was developed by IBM and Motorola. In the past, after wiring was formed by etching an AI film convexly, an interlayer was filled with an insulation film. As against it, in the Dual-Damascene interconnect technology, after a flat interlayer insulation film is trench-etched according to an interconnect pattern and a Cu thin film is electroplated/deposited on the entire surface, the electroplated/deposited Cu is polished by the Chemical Mechanical Polishing (CMP) so that interconnects are formed with the Cu remaining only in a trench portion (for example, “Next-generation ULSI Process Technology”, Realize Co./Tokyo, Feb. 29, 2000, pp.558–565).
In this Damascene interconnect technology, application of a low dielectric constant insulation film is essential. As low-k insulation films, an inorganic SOG film deposited by a spin coat process, an a-C:F film deposited by a plasma CVD method using CxFyHz as a source gas, or a SixCyOz film deposited by a plasma CVD method using silicon-containing hydrocarbon as a source gas, etc. are known.